Flexible-wall packages are ubiquitous in today's world. In addition to commonly being disposable, these packages offer a virtually-endless variety of shapes, sizes and configurations. Such packages or pouches are commonly used to store food items. To verify the projected shelf-life of the product, a need has arisen to test non-destructively the integrity of the seal.
Others have attempted to address this problem. Some of these earlier solutions have contemplated that the package-to-be-tested be placed within an enclosure. The enclosure is then evacuated to create a pressure differential such that air or gas will tend to escape from the package. A sensor is used to monitor movement of a movable wall portion of the package, and, in turn, indicates whether leakage has occurred. Examples of such prior art devices are shown and described in U.S. patent application Ser. No. 914,239, filed Oct. 2, 1986; in U.S. Pat. Nos. 3,751,972, 3,837,215, 4,517,827, 3,918,295 and 3,117,441; published in British patent application No. 2,059,381A; and in published French patent application No. 2,351,400.